No that's perfectly possible. The original mould will have had Hong Kong on it but when the mould was being used in a different country to produce the pony, the manufacturer would have melted/obscured the "Hong Kong" on the mould so that it did not show.
Hence why sometimes you can see a faint impression.
Its the same reason why some countries have their name in almost scratched hand writing showing - because it was not part of the original mould so was added by the manufacturer. There are quite a few Nirvana ponies who sometimes turn up with Hong Kong stamps visible on them
Greeks can be a little notorious for it.